The present invention relates to an information recording reproducing apparatus and method for recording and/or reproducing information. More particularly, the present invention relates to an optical-disk recording apparatus and method for recording information in an optical disk serving as a recording medium, an optical-disk reproducing apparatus and method for reproducing information from an optical disk, and an information recording system and method using an optical-disk recording apparatus in combination with an external unit. 2. Description of the Background Art
An optical disk has gained attention as a large-capacity information-recording medium, and the development and commodification of the optical disk has progressed as an external memory device of a computer or an audiovisual recording medium. In general, an optical disk has spiral or concentric tracks formed on the disk surface. and records or reproduces information by applying a laser beam along the tracks. Moreover, each track is further divided into a plurality of sectors respectively serving as the minimum unit for recording or reproducing information data. Address information is previously recorded in each sector so that a position on a disk can be univocally specified and a recording/reproducing apparatus makes it possible to record or reproduce information in sector units by reading address information from the disk.
FIG. 18 is an illustration showing a data format in a sector of a rewritable optical disk having been recently practically used in a case of a DVD-RAM as an example. As shown in FIG. 18, a sector 1001 includes a header field 1002 and a data recording field 1003. The header field 1002 has an address field 1004 and a mirror field 1005 and the address field 1004 is further divided into four address-fields, that is, first to fourth address-fields 1004a, 1004b, 1004c, and 1004d. Each address-field is constituted of address VFO fields VFOa, VFOb, VFOc, and VDOd (hereafter referred to as VFO field), address mark fields AMa, AMb, AMc, and AMd (hereafter referred to as AM), address information fields PIDa, PIDb, PIDc, and PIDd (hereafter referred to as PID), error detection code: fields IEDa, IEDb, IEDc, and IEDd (hereafter referred to as IED), and, postamble fields PAa, PAb, PAc, and PAd (hereafter referred to as PA) from the head in order. The data-recording field 1003 is constituted of a gap field 1006, front guard field 1007, data VFO field 1008, pre-sync code field 1009, data field 1010, data postamble field 1011, rear guard field 1012, and buffer field 1013.
The contents and functions of each of the above fields are briefly described below. First, the header field 1002 is an field for univocally specifying the position of each sector 1001 (that is, address) on an optical disk, in which a pattern for recognizing an address by a recording/reproducing apparatus is recorded by previously forming an irregular pit shape in each field to be mentioned below. A single pit pattern for quickly performing lead-in of PLL in a reproductive system of the apparatus is recorded in the VFO field (VFO) among fields constituting the address fields 1004a to 1004d of the header field 1002. The single pit pattern uses, for example, a continuous pattern of 4T-mark•4T-space. Herein, “T” denotes a channel bit cycle, “mark” denotes a pit, that is, a concave portion, and “space” denotes a mirror, that is, a convex portion. In this case, it is also permitted to reverse definitions of a mark and a space.
A specific pattern showing a start of address information is recorded in the address mark field (AM) and is used to correctly make bite synchronization of each of the address information fields (PID) immediately after in the apparatus. Address information is recorded in the address information field (PID). The address information includes at least an address number for univocally specifying the position of each sector on an optical disk and moreover, includes additional information showing the attributes of sectors and an nth address information field among four address information fields in each sector.
An error detection code (parity) is recorded in the error detection code field (IED) for detecting a bite error in the address information field (PID) immediately before. For example, a Reed-Solomon code or cyclic code is used as an error detection code, and address information error detection coded data is reproduced by adding an error detection code to address information, and by passing through an error detecting circuit a pattern of the reproduced address information error detection coded data (i.e., address information PID+error detection code IED), it is possible to easily detect an error included in the pattern. A specific pattern which indicates an end terminal of each address field is recorded in the postamble fields (PA).
A modulation code obtained by modulating address information and binary data of an error detection code in accordance with a predetermined modulation rule is actually recorded in each address information field (PID) and each error detection code field (IED). The rewritable optical disk of this example uses an 8/16RLL(2, 10) modulation code as a modulation code to be recorded in each address information field (PID), error detection code field (IED), and data field 1010 in the data recording field 1003. In this case, 8/16 denotes that 8-bit binary data is converted to 16 channel bits. Moreover, RLL is the abbreviation for Run Length Limited and denotes that a run length, namely, the number of symbols O to be inserted between symbols 1 is finite when expressing a channel code by NRZ (Non Return to Zero). In the case of RLL (2, 10), a run length is limited so as to have a value ranging from 2 to 10. The rewritable optical disk of this example records data in the form of NRZI (Non Return to Zero Inverted), and therefore, in other words, in the case of RLL (2, 10), it can be said that lengths of a mark and a space are limited in a range from the minimum length 3T (two zeros) to the maximum length 11T (10 zeros). In the case of this example, 3T is referred to as a shortest mark Tmin and 11T is referred to as a longest mark Tmax.
Among the fields constituting the data recording field 1003, the gap field 1006 is an field formed as a time margin for post-processing for reproducing address information from the header field 1002 of the apparatus and pre-processing for recording data in the subsequent fields below the front guard field 1007, but data to be reproduced is not recorded herein. The front guard field 1007 and rear guard field 1012 fieldreas for absorbing deterioration of a recording film that occurs when repeatedly recording data in the same sector, in which a specific repetitive pattern is recorded. The data VFO field 1008 is for recording a single pit pattern for quickly performing the lead-in operation of a reproductive-system PLL when reproducing data. In the case of this example, a continuous pattern of 4T-mark•4T-space same as the case of each VFO field of the header field 1002 is recorded in the front guard field 1007, data VFO field 1008, and rear guard field 1012.
The pre-sync code field 1009 records a pre-sync which is a specific pattern provided to detect the head of the succeeding data field 1010 and easily make bite synchronization. The data field 1010 is an field for actually recording user data, which is constituted of a plurality of sync frames in order to secure reliability of bite synchronization though not illustrated, and a sync code serving as a specific pattern is added to the head of each sync frame to facilitate the bite synchronization in each sync frame. Moreover, an error detection code according to a predetermined code rule is added to the user data recorded in the data field 1010 and the user data is recorded after the user data is modulated by using an 8/16RLL(2, 10) modulation code same as that used for each address information field (PID) and each error detection code field (IED) of the header field 1002. The data postamble field 1011 records a specific pattern showing the end of the data field 1010. The buffer field 1013 is an field for a time margin provided so as not to overwrite a header field immediately after even if a linear velocity is changed due to a factor such as rotational fluctuation or eccentricity of a disk when recording data, but data is not recorded in the field 1013.
Then, a method is described below which is used for a conventional optical disk drive when recording/reproducing data in or from a rewritable optical disk having a sector structure of a data format as described above.
In the case of a conventional optical disk drive, when recording/reproducing data in or from a predetermined sector 1001, the position of the predetermined sector 1001 on a disk is first specified by identifying address information from the header field 1002 to generate a timing for actual recording or reproducing in the data recording field 1003 after the above error detecting circuit detects that a pattern of the address information to which an error detection code is added, that is, (address information+error detection code) does not includes an error.
Moreover, in the case of the conventional optical disk drive, to record data in the predetermined sector 1001, it is a condition for recording data in the sector 1001 that there is no error in address-information-error-detection coded data in at least an address field, that is, at least a pattern of (address information+error detection code). That is, when there is an error in the pattern of (address information+error detection code) in every address field of a sector in which data will be recorded, the sector is judged as a defective sector and data is not recorded in the sector but the processing for substitution-recording data in another sector instead of the defective sector is performed.
Moreover, in the case where there is an error in the pattern of (address information+error detection code) in every address field of the predetermined sector 1001 when reproducing data from the sector 1001, it is impossible to correct a sector sync counter in the sector and therefore, by using an output of a sector sync counter corrected by a sector having at least one address field in which an error is not detected in the pattern of (address information+error detection code) immediately before the sector 1001, the timing necessary for reproducing the data of the sector is interpolated and reproduced.
As described above, the conventional optical disk drive cannot execute recording when there is an error in every address field of a sector to which data will be recorded. Therefore, the substitution processing of recording the data to be recorded to another sector must be executed, and a problem occurs that a lot of processing time is necessary and the recording throughput lowers. Particularly, when the data continuously input such as AV data is recorded to an optical disk, a fatal problem may occur that data is lost or recording must be interrupted because the data-recording speed cannot be ready because of the substitution processing due to an error in an address field.
Moreover, the conventional optical disk drive corrects a sector sync counter at the timing at which it is detected that there is no error in at least one address field of each sector and generates the timing required to record or reproduce data, and therefore it is necessary to generate a timing by interpolating the timing obtained from a sector in which there is no error in an address field immediately before in the case where there is an error in every address field of a sector from which data will be reproduced. Therefore, a problem lies in the accuracy of the data-reproducing timing. Particularly, when sectors having an error in every address field continuously occurs, a shift occurs in a timing signal necessary for detecting the first of data such as the above pre-sync detection window signal and there is a danger that a pattern may not be detected or may be erroneously detected. Moreover, in the worst case, a fatal problem may occur that a plurality of frames at the head of a sector are lost and thereby, a data error cannot be corrected and data cannot be reproduced.
Moreover, in the case of an information recording system for recording information in an optical disk having the data format shown in FIG. 18 by combining the optical disk drive with a host computer, fieldl-time characteristic, that is, a predetermined transfer rate is generally requested for the operation for recording AV data in the optical disk. However, the real-time characteristic is not always requested for the operation for recording computer data to be handled by a conventional personal computer in an optical disk but occurrence of an error is not permitted because even a small data error in computer data may give a fatal influence to a system.
In the case of the information recording system for recording the information including AV data having the real-time characteristic and the computer data which cannot permit an error in an optical disk, it is assumed that data errors include two types such as a data error and an address-information error.
For the data error, the idea of assuring the quality of recorded data by verifying the data is applied in the case of a conventional apparatus, however, in performing verification, a problem occurs that the normal-recording-sequence execution time increases.
For the address-information error, data is not recorded to a sector in which errors equal to or more than a predetermined number of errors are detected in address information in the conventional apparatus. Moreover, the data is generally recorded to the sector through retrying process. However, the recording-sequence execution time is increased due to retrying of recording to the same sector or alternation recording processing, a problem occurs that a data transfer rate for recording is deteriorated.